Lock



Feb. 17, 1931. Q RDER 5' 1,793,440

LOCK

Filed April as, 1929 s Sheets-Sheet 1 Feb. 17, 1931.

o. HARDERS 1,793,440

LOCK

Filed April 23, 1929 3 Sheets-Sheet 2 wmP m-7 IN V EN TOR.

' Patented Feb. 17, 1931" This invention relates to looks and morein particular tomethods and means :for operating locks electrically.

One of the primary objects of this inven-. 5 tion is to devise a lock whichmay be closed or opened electrically, withoutt-he use of an ordinary key. Another object is to provide with a lock of this character a master switch havingseveral contacts which must be closed may be operated,.and in which the sequence of operation of said contactsand the -numbers thereof may. be varied by the owner Yet another ob-,

will appear from the iollowingdescription considered in connection .with the accompanying drawings forming a part of this, .ap- P 1 Fig. 1 is a sectional elevation taken through the median line ofa master-switch ada ted to be used in connectionwith an electric ock intended especiall for 1 residences, stores, banks, etc. This gure also includes'a side elevation ofa special master key whichLmay be used, if desired, inconnectionwith the master switch..

Fig. 2 is a top plan view of master-key being omitted. 1

Fig. 3 is a top plan view of themasterkey.

Fig. 4,-is aplan viewof the contact-base of the master key shown in Fig. 1.

Fig. 5 is a side elevation showings. grou of five electromagnets .used for-makingan breakin certain electric circuits, to bedescribed ater. y I

' Fig. 6 is a view showingthe interior of the electric lock used in this invention.

- Fig. 7 is a sectional elevation showing a. modified construction for a master-switch :to be used in place of the one shownin'Fig. 1; 'a master key being also shown in elevation.

Fig. 8 is a top plan view of Fig. 7, the master key being omitted.

Figs; 9 and 10 are topplan views respec- Fig. 1, the

in a pre-established sequence before the lock cation and mwhich .l

. tively of the lower andynplper Safety discs used of themaster-switch, Fig. 7.1

Fig. 11 is 1 another :modifiedrconstruction of: 1a .-m aster-switch, intended especially for use on private. closedautomobiles, ambulances or police patrol wagons,-etc., provided with myinvention.v

Fig, 12 is a fragmentary top view of Fig. 11.

Fig.13is a top'plan vicwof the lower contact base; shown in Fig.11; the various contact-levers beingomitted. 4 I b .Fig. 14. is atop plan of the upper contact ase- Fig. 15 is a replica of Fig. 6. i

Fig. 161isa plan view of a switch-lever used in the electric lock." I

Fig-1'17 is an end elevaticnci Fig.16.

Fig; A is, ,aninclusive .view showing the electrical wirin connections used preferably for house insital ations. I

Fig. B is a. similar :view showing the electrica' wiring connect-ions in: the a plication 05( my invention toclosed automobi es and the e.- a

.Themasterswitchgshown in Figs. 1' to 3 comprises a housing l,'p,referably cylindrical, having a base 2, a-to 3 and an intermediate guide-plate 4 all pre erably made of electric insulatingmaterial.

In the mastersswitchare mounted several switches ten in the present embodiment) in- .dicated iagramatically. in Fig. 4 vby the -romanfnumerals [I to X,.each switchcomprising a longitudinally movable contact plug P adapted to engage terminals .0 conhelld into Y raised -.position, away from their terminals, by springs 5 resting on the plate 42nd acting on co'llarsB iastenedto each plug. To operate a (lock, .it is. necessary, in the number to .contact-plugs flour in the anus trated example) i sisting each of two; contact clips, fastened on. the base 2 and indicated by the .suflixes a and 10 applied to their correspondingswitch numbers. The contact plugs are normally If desired, the master-switchmay be sup- I plied with .a master key 7,. in which four suitably spaced and'insula ted pins Bare secured material. Ten contactlugs P are also used which are normally hel in non-operative position by the coil springs 5, inserted between the plate 14 and the flange collars'6 on the plugs. These plugs are guided for longitudi-' nal movement in suitable apertures provided in the intermediate plate 14 and the top 13. Mounted for rotation in the center of the rims ter-swich is a spindle 15 having secured at the top an indicator-hand 16 pointing toward the various contact plugs, which, of course, are numbered consecutively from I to X;

At the bottom end of the spindle and secured thereto is the lower safety disc 17 having ten apertures 18 suitably spaced to be enaged by the contact-plugs when depressed. reely mounted about the spindle and resting on the lower safety disc is the upper safety disc 19 in which are provided ten apertures 20 spaced to register with the apertures 18 in the lower disc and an extra aperture 21 spaced half-way between two apertures 20.

On the lower disc 17 is fastened a -tab 22 having an aperture 23 and on the upper disc 19 is secured a wider tab 24 having two apertures 25 and 26 respectively disposed in radial alignmentwith the aperture 21 and the next ad]acent aperture 20 on the upper disc, and

. each adapted to re ister with the aperture 23.

The purpose of t e two safcty'discs is to enable pressing the number of contact plugs required to o erate the electric lock (four in the presentem diment) either one at a time in the proper sequence, or all four simultaneously by means of a master key. Thus, when the upper and lower safety (lISCS are clamped to- .gether by inserting the clamping screw 27 through the apertures 26 and 23 in the tabs 22, 24, the ten evenly spaced holes 20 in the upper disc will register with the holes 18inthelower disc anda master key may be used to press down simultaneously the four required 0 erating contact plugs. On the other ban by inserting the clamping screw 27 through the apertures 25 and 23, the top disc will be shifted around so that only the aperture 21 in the top disc and one aperture 18 in the lower disc will register, the other nine apertures 18 being then covered by the top disc. This will allow the pressing of but one contact-plug at a time by moving the indicator hand consecutively and in the proper sequence toward the four operative contact-plugs.

It will be noted in Fig. 7 that the contactplu s are normall held, by their coil springs 5, a ove the to o the upper safety disc 19 to permit of the rec rotation of the hand 16 and discs 17, 19. The master-key, 'for this switch comprises aplate 28 having ten threaded apertures 29 in four of which are inserted the press-pins 30 suitably located to act on the four predetermined operating contact-plugs. This master-key is guided by means of two guidestuds 31, 32 of different diameter and engaging corresponding apertures 33, 34 provided in the plate 28. Shoulders 35 are provided on the guide-studs to limit the downward push of the master-key.

The clamping screw 27 is made sufliciently long to engage, when desired, an aperture 36 drilled in the base 12. Thus, if the masterswitch is to be operated by a master-key alone, the safety discs 17, 19 may be held permanently in proper register by screwing the clam ing screw'in the hole 36, in this case the in icator hand 16 would be removed, as useless. Also, by inserting the clamping screw through the holes 25, 23 and 36, the masterswitch can be locked into inoperative position, since only one of the ten contact-plugs could be pressed down.

When'the electric lock is to be operated, as in this embodiment, by four contact plugs, a battery comprising four circuit closing electro-magnets and one circuit breaking electromagnet is used. As shown in Fig. 5 these magnets are mounted, preferably, on a common'frame composed of a top bar 37 and a bottom bar 38 held in proper distance by the posts39. The first electromagnet 40 is the circuit breaking magnet and 41, 42, 43 and 44 arethe four circuit closing electro-magnets.

Each magnet has an iron plunger 45 having at the bottom a cross piece 46 adapted to electrically connect together the contact terminals T. At the upper end 0t each plunger is secured a collar 47 having two para lel sides slidably engaging the walls of a-stirrup 48 mounted on the top bar 37. The purpose of this collar is to prevent the rotation of each plunger within the solenoid of the electro-magnet and to limit the travel thereof.

The electric lock shown in Fig. 6 consists of a housing 49, a lock-bolt 50 suitably guided for longitudinal movement and a sliding plunger 51 having a round end adapted to engage the jamb of the door which causes this plunger to be, pushed in. The bolt has a lateral extension 52 to which is centrally secured a magnetic core-53 extending on both sides into the solenoids 54, 55 suitably fastened to the housing.

The plunger 51 is normally pushed outwardl of the housing by a coil spring 56 place intermediate a collar 57 formed 'on the plunger and the outer guide stirru 58. Upon this plunger is rockably mounted a out the fulcrum pin 59 a. bell-crank lever 60 having at the rear a long arm 61 terminatingv with an angularly disposed finger 62 and at the front another arm 63. This lever is held in normal position by a spring 64 and its clockwise rotation is limited by a stop-pin 65 fastened on the plunger. .The finger 62 is engaged by a lentil shaped wedge 66 mounted on the extension 52 when the bolt is forced out. When the bolt is forced in by the solenoid 55 the wedge 66 will separate the contact clips 67 68 which normally touch each other. The wedge 66 is made of any suitable insulating material.

The arm 63 of the bell-crank lever is adapted to engage the insulated end .69 of a switch lever 69 (Figs. 16, 17) fulcrumed at 70 and cause the same to engage a contact 71. Thislever is normally held away from said contact by a spring 72 and its rotation in a clockwise sense is limited by a pin 73. The purpose of providing the insulated end on the switch-lever is to prevent any electric current passing through the lever 60.

At the lower end of the housing are suitably fastened and spaced the electro-ma-gnets 74, 75 provided respectively with the hinged armatures 76, 77 upon which are secured insulated switch blades 7 6, 77 adapted to engage their corresponding contacts 78, 78 and 79, 79. The armatures, therefore, carry no current; they are normally held into lifted position by coil springs 80 and bear then against stop pins 81. On the under side of the lock-bolts are two lugs 82, 83 adapted to be engaged respectively by the armatures 76. 7 7 to prevent the bolt, when in locking position, to be pushed in, and also to prevent its flying out by centrifugal "force when the door is swung about rapidly, and the bolt is in retracted position.

As stated, the master-switch shown in Fig. 11 is intended especially for use on closed automobiles. This switch consists of a housing 84 a base 85, a cover 86 and an intermediate plate 87. Ten contact-plugs (P") are also used.

Each contact-plug acts upon a switch-blade 88 fulcrumed on brackets 89 mounted on the base and is adapted to engage the so called blind terminals B also mounted on the base 85. The contact-plugs are normally held in raised position by springs 90 mounted as shown, whereas the switch-blades are normally held in engagementswith their corresponding blind terminals by springs 91.

When pressed down, each contact-plug will cause its switch blade to engage an up per terminal L which is the operating :or live contact by means of a suitably shaped resilient catch 92 provided at the outer end of a lever 93 fulcrumed in a stand 94 and .nected to the clip III".

normally held in the lowered position shown in the. drawing by a spring 95.

When all the contact-plugs required to completerthe necessary connectionsto operatethe lock (four in this case) have been pushed in,

the switch-blades may be broughtsimultaneously back into inoperative position by pressin on the centrally disposed push-rod 96 having at its lower end a disc 97 acting on theraised inner ends of the levers 93. This will cause'the catches 92 to release said switch-blades after having broken their engagements with the live contacts. It will,'of course,'be understood that this switch could be modified to be operated by a master-key,

in a same manner as was done with the above a residence, as per Fig. A, and. thatthe master-switch be connected for the combination of contact-plugs at V, X, VII and III operated successively, the operator will first press the contact-plug at V, whereby the following circuit will be established: From the pole B of any suitable and desired source of electrical energy, via wire 100 to the contact-clips V, V, wire 101, solenoid 44, wire 102, contact clips 68 and 67, wire-103 terminal 104 of solenoid 40 cross-piece 46, terminal 105, down wire 134 and to the pole +A of the .supply'circuit, The solenoid 44 is, therefore, energized, thus connecting the terminals 106,

107 byvits cross-piece 46. From 107 a wire 108 leads to the clip X. of the master-switch. The contact-plug at X is then pressed down and another circuit is established, viz: From the contact-clips X", X, via wire 109 through thesolenoid 43, wire 102, contact-clips 68 and 67, wire 103, terminal 104 cross-pieoe 46, terminal 105, wire 134'and to thepole +A of the supply circuit, .Hence the solenoid 43 is energized and its cross-piece 46 connects the terminals 110, 111. From 111 a wire 112 goes to the clip VII on the master-switch.

Contact-plug at VII is now pushed in and the following circuit is set up: From the contact-clips VII", VII ,'via wire 113, solenoid 42, wire 102, contact-clips 68 67 wire 103,

terminal 104, cross-piece 46,. terminal 105,

wirev 134 and to the pole +A of the supply system. The energized solenoid 42, by its cross-piece 46, connects theterminal 114, 115, and from the latter a wire 116 is con- The contact-plug at III is the last to be pushed connections: From III", III, by way of the wire 117 to solenoid 41, wire 102, contactclips 68,

zes the solenoid'41-. rom wire the terminal 119 and the latter is connected by the cross-piece 46 to the terminal 120. Thence, a wire 121 leads to the electro-magnet 74in the electric lock (Fig. 6) and from 74 a wire 122 goes to the (pole +A. This magnet is thus energized an attracts its armature 76 which engages the contacts 78 and 78", The contact 78 15 connected by a wire 123 to the wire 121 and the contact-78 is connected the wire 124 to the solenoid 55 of the lock-bolt. Another wire 125 connects the solenoid to the pole +A. a v

The solenoid 55 is now energized; lt-pulls in the lock bolt and the door may be opened. The insulated wedge 66 has now enga ed the contact clips 67, 68 and separate them,'therebyinterrupt1ng the current through the soslenoids 41, 42, 43, 44, and the master switch-is again ready for 'operation. p a I As stated'betore, as soon as the contactnets 44,43,42 and-41 even after the rising of released, a cross wire 126 is connecte wire 108, wire 126,t

lugs at V, X, VII and III are released after avmg been pushed in, they will be forced -up into inoperative position by their coilsprings 5. With the wiring conditions so 'far described, the electric lock could not be operated unless all the active contact-plugs were kept down.- Provision is, however,

made to maintain their corresponding magan energized state,

the contactplugs,

in the following manner:

- To maintain the solenoid 44 energgirzed when its corresponding contact-plu t is o e wires 101 and 108,; will enable a current to flow from the le --B, via wire 100, terminal 106, cross 1ece'46, terminal 107, rough the solenoid 44, the wire 102 and, in themanner repeatedly described, to the 16 {:A of the's'upply7 line, withoutpassing rough the contacts V' of the master switch. s i When the contact-plug at X is released its electro-m'agnet 43 will remain energized by a current passing a wire 127, to the terminals 110,111, wire 112, cross-wire 128, to wire I09, solenoid 43', wire 102, and thence to the pole +A. Similarly for the contact-plug at VII; by connecting terminals 111 and 114 by a wire 129 and connecting wires 113 and 116 ,by the. cross-wire 130 current will flow from the pole B through the solenoid 42, wire 102,

and finally back to the su ply system'at +A.

Of course, as soon as t e last contact plug at III is pressed down, the door-bolt will be operated; it will remain in its assumed posiin and'it establishes the following 67, wire 103 terminal 104,cross-piece' 46, terminal 105, wire 13.4, to the ole +A.' v This ener 117 branc cs 06. a wire 118which leads to III),

solenoid 40,

. the pole -B.

be energized, its cross-piece 466 pulled up and between the terminals 104, a .105 would be broken, with the result that from line 108, though means tion :he dontact-plug at III into inoperative posiion. I:

. It is not possible to operate the lock unlessv the four contact-plugs be pressed down in the exact sequence for which the master-switch is wired. Thus for instance, if one should press the contact plug at VII before (instead of after) the contact-plug at X, the latters solenoid wouldlnot be energized and, therefore, its cross-piece 46 would not establish the electric communication between'the terand will not be afiected by the return of minals 111 and 114 (via wire 129) necessary a to energize the solenoid 42 which corresponds to the contact-plu at VII.

The purpose 0 the circuit-breaking sole- Y no1d 42 is to deenerglze the four circuitrnaking solenoids 41 to 44 in case a wrong contact-plug of the master-switch is pressed down.

For instance, if should, by good luck, ri ht sequence,

press down in the the lished: From the pole +A, wire 134, through wire 135, circular wire 136, contacts I, I, circular wire 137, wire 100, and to Hencethesolenoid 40 would the connection the electric circuits throughthe three, already energized, solenoids would be destroyed, and the whole process of pressin the control-plugs would have to be repeated.

the first'three contact-plugs at X and VII, and then erroneously pres the contact-plug at I (instead of the one at. following circuit would be estab-' I 85. an unauthorlzed person As an additional safety, I have introduced in the wiring. s stem an alarm-bell 138 -(or other deslre electric signalling, device) which gives a warning signal as soon as the third contact-plug VII has been pressed down. This bell is connected by a wire 139'to the cross-wire 130,'which connects. in the manner already described to the pole -B,'and b V p the wires 1'40, 134, down to the pole Therefore, when the solenoid 42 is ener ized, the bell rings.

Durin day time when t e door is frequently such as in a store in which attendants opene 7 are present, it ma ,not be necessary to make use of the signal ell, andthe latter. may be disconnectedby 'o eningthe switch 141.

The house-switc 131, which is connected by wires 132, 133 to the poles B and +A. is used to open the'electric loci: from within the house, independently of the masterswitch. When closing thishouse-switch, the path of the electric-current to the electric lock will be as-fol1ows: From the pole -B via wires-100, 132, through switch 131, wire 133,-wire 121, through the electro-magnet 74, wire 122 to the pole +A; whereby the electromagnet 74 is energized. This estab lishes another clrcuit, as follows: From the pole +A, via wire 125, to solenoid 55, wire 124, contacts 78, 7 8, switch-blade 7 6, wires 123, 121, 133, throu h switch 131, wires 132 and 100 to the ole Hence the energized solenoid W1 I pull in the door bolt 50 and the door may be opened.

The door may also be locked from within the residence, rovided it has" first been closed manually, or by means of any type of commercial door-check. The closing of the door pushes the sliding-plunger 51 of the electric ock inwardly, whereby the lever 69 engages the contact 71, being acted upon by the arm 63 of the bell-crank lever 60.

A hand switch, (or any type of automatic time switch) 142 is connected to the pole B by a wire 143. The closing of this switch establishes the following circuit: From the pole B, via wire 143, switch 142, switchlever 69, contact 71 wire 144, wire 148, through the solenoid 7 5 and wire 145 to the pole +A. This energizes the solenoid 75 and its armature 77 engages the contacts 79, 7 9 thus closing another circuit which runs as ollows From +A, wires-134, 146, through the solenoid 54, wire 147, contacts 7 9, 79, wire 144, contact 71, lever 69, and wire 143, switch 142 to the pole -B. The solenoid 54 is energized and the door-bolt 50 is forced out by it into locking position. At thus instant, the wedge 66 presses on the finger 62 of the hell-crank lever which turns counterclockwise, thus releasing the'switch lever 69 and breaking its engagement with the contact 71. Hence, the current passing i 7 through the solenoid 54 is interrupted.

- When the bolt is in locking position, the

: armature 76 of the solenoid 74, by the action of its spring 80 will assume a position in back of the 111 82, thus preventing the backward forcing o the door-bolt.

My invention as up lied to automobiles differs from the embo 'ment just described in that the operative contact-plugs of the master-switch remain in their ushed-in position until the push-rod 96 as been depresfld, and the wiring is considerably simli e p Referring to Figs. 11 to 15 and the diagram Fi B, it has been assumed that the door is locked and that the combination of the contact-plugs to be operated to open the lock be X, III, VII and IV, which contact-plugs may be, in this case, operated in any desired sequence, since they are all connected directly in series.

When all four contact-plugs are pressed down, the electric current runs as follows: From the pole +A of any source of electricity, such as a storage battery, through wire 150, the contact-plugs at X, III, VII and IV, wire 159, contacts 67, 68, wire 151, wire 156, solenoid 74, wire 152, ring-wire 153 (Fig. 13) through the blind contacts at I, IX, VIII, VI, V andII, and wires 154, 155

to the pole -B. The solenoid 74 is energized; its armature 76 is attracted and engages the contacts 78 and 78, thereby establishing the following circuit: From the pole +A, via wires 150, 165, switch 164, wire 156, contacts 78, 78, wire 157, bolt solenoid 55 Wire 15s to Wire 1522, through the six blind contacts, Wires 154, 155 and to the pole B. Therefore, the energized solenoid 55 .pulls in the door bolt 50 and unlocks the door.

'When the door is shut close, it is automatically bolted or locked by the agency of the sliding plunger 51 which is pushed in. As

explained before, the switch lever 69 then engages the contact 71 and closes a new circuit, as follows: From the pole +A, wires 150, 201, 200, switch 69, contact 71, wire 160, solenoid 75, wires 152, 153, the six blindcontacts wires 154,155 to the pole -B.

The solenoid 75 is energized and the attracted armature 77 closes another circuit, to wit: From +A, wires 150, 201, 200, switch 69, contact 71, wires 160, 203, contacts 79, 79, switch-blade 77, wire 162, through the solenoid 54, wire 163, wire 152, and the pole B. Solenoid 54 is energized and the bolt 50 attracted by it locks the door. When the bolt is forced out, the wed e 66 engages the bell-crank lever 60, thus reaking the engagement between the switch-lever 69 and the contact 71 and interrupting the current passing through the solenoid 54.

As soon as the four operative contact-plugs P have been pushed in and the door bolt shifted, the operator of the master-switch will press on the center push-rod 96 to bring said contact-plugs back into normal inoperative position and in engagement with their respective blind-contacts.

To open the look from the inside of the closed automobile, a normally open switchwhich runs in the following manner: From the pole +A, via wires 150, 165, switch 164, wire 156, contacts 7 8, 7 8, wire 157 solenoid 55, wires 158, 152, through the six blind contacts, wire 155 and to the pole B.. The solenoid 55, therefore, attracts the bolt 50 and the door may be opened.

The use of switch 164 is especially recom mendable for police patrol wagons, where it would be installed in some recondite place known only by one of the accompanying police guards. overpower his guard or guards, he would not be able to make his escape from the patrol Should a criminal be able to wagon, on account of his ignorance regarding the location or existence of said switch.

An alarm signal, such as the bell 166 is also shown to sound a warning as soon as the third active contact-plug has been depressed. The positive pole of this bell is connected by a wire 167 to the wire 168 which starts from the third contact (at VII) and leads to the pole +A. The negative pole is directly connected by a wire 169 to the wire 152 and the pole B. A switch 170 is also placed in line 169, to disconnect the bell, whenever desired.

It is, of course, understood that the various contacts and contact-levers, etc., in the electric lock must be properly insulated from the housing of the lock to establish the several electric circuits described above. The insulation of said cont-acts, etc., may be obtained by securing into the lock-housin one or more plates of insulating material %not shown) upon which the contacts, etc., would be mounted.

In the aforesaid it has been assumed that a single electric lock be fitted to a door. However, if desired, two or more such locks might be placed on each door and operated simultaneously from one master switch. The electrical connections required for this arrangement will be readily conceived by those versed in the art, assisted by the description given hereinabove.

As will be understood, as suggested herein, there may be slight changes made in the construction and arrangement of the details of my invention without departing from the field and scope of the same, and I intend to include all such variations, as fall within the scope of the appended claims, in this application in which only two specific forms of my invention have been disclosed.

I claim: 1. In combination with an electric lock having a bolt operable by electro-magnets,-

a plurality of preliminary electric circuits; a circuit-closing solenoid in each preliminary circuit; a switch means in each of said preliminary circuits adapted to close the electric circuit of its corresponding solenoid, and electric connections between said solenoids and electro-magnets; one of said electro-magnets being energized after the closing of all circuit-closing solenoids.

2. In combination with an electric lock having a bolt operable by electro-magnets, a plurality of preliminary circuits; a circuit closing solenoid in each preliminary circuit; a switch means in each of said preliminary circuits adapted to close the electric circuit of its corresponding solenoid; means to normally hold each switch means in open position; electrical connections between said solenoids and electro-magnets adapted to energize one electro-magnet after the closing of all circuit-closing solenoids, and electric connections adapted to maintain the solenoids energized after their corresponding switch means resume their normal open position.

3. In a system for actuating an electric lock operated by electro-magnets, a master-switch comprising a plurality of switch means disposed concentrically in spaced relation; means for normally holding said switch means into open position, and unitary means for closing simultaneously a plurality of switch means.

4. In a master-switch for operating an electric lock, the combination of a plurality of contact-plugs; contact-clips therefor; means to guide said plug for longitudinal movement; means adapted to normally hold said contact-plugs distant from their corresponding contact-clips, and unitary means to connect simultaneously several contact-plugs with their corresponding contact-clips.

5 In a master-switch for operating an electric lock, ahousing; a top and bottom therefor; a. guide-plate positioned intermediate said top and bottom; a plurality of contact-plugs disposed concentrically and guided for longitudinal movement by the top and said guide-plate; a plurality of contactclips mounted on the base and adapted to be engaged by their corresponding contactplugs; means for normally holding said plugs distant from their contact-plugs; a centrally disposed rotatable spindle; a lower safety disc secured to said spindle and an upper safety disc. freely engaged by the spindle, bearing on the lower disc and rotatable thereon,

said safety discs having evenly spaced apertures adapted to be engaged simultaneously by the contact-plugs and the upper safety disc having an additional aperture disposed intermediate two of said aforementioned apertures and registerable with either one of the apertures in the lower disc, and means to secure said safety discs into selected relative position.

6. In an electric lock, a door-bolt having a lateral extension; a magnetic core fastened to said extension and extending on both sides thereof; a solenoid positioned on each side of said extension and engaged by its corresponding portion of said core, and an electric system comprisin electro-magncts and contact-making and reaking means adapted to close an electric circuit through said bolt actuating solenoids.

7. In a master-switch for operating an electric lock, a housing; a top and bottom therefor and an intermediate plate; a plurality of contact-plugs disposed concentrically and guided for longitudinal movement by said top and intermediate plate; a plurality of rockable switch-blades mounted on the base each adapted to be operated by a contactplug; a plurality of lower contact-clips also mounted on the base; means to normally hold the switch blades into engagement with said lower contact-clips; a plurality of upper contact-clips mounted on the intermediate plate and each adapted to be engaged by a switchblade when actuated by its corresponding contact-plug; means to hold each switchblade in engagement with its upper contactclip, and unitary means for simultaneously returning the switch-blades engaging the upper contact-clips into engagement with their lower contact-clips.

n testimony whereof I aflix my signature.

OTTO HARDERS. 

